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It is well established that agents which inhibit the 20 transport of bile acids across the ileum can also cause a decrease in the level of cholesterol in blood serum. Stedronski, in “Interaction of bile acids and cholesterol with nonsystemic agents having hypocholesterolemic properties,” Biochimica et Biophysica Acta, 1210 (1994) 255- 25287, discusses biochemistry, physiology, and known active agents affecting bile acids and cholesterol.

A class of ileal bile acid transport-inhibiting compounds which was recently discovered to be useful for influencing the level of blood serum cholesterol is 30 tetrahydrobenzothiepine-l,l-dioxides (THBDO compounds). (U.S. Patent Application No. 08/816,065)

Some classes of compounds show enhanced potency as pharmaceutical therapeutics after they have been enantiomerically-enriched (see, for example, Richard B. Silverman, The Organic Chemistry of Drug Design and Drug Action, Academic Press, 1992, pp. 76-82) . Therefore, THBDO compounds that have been enantiomerically-enriched are of particular interest.

A class of chemistry useful as intermediates in the preparation of racemic THBDO compounds is tetrahydrobenzothiepine-1-oxides (THBO compounds) . THBDO compounds and THBO compounds possess chemical structures in which a phenyl ring is fused to a seven-member ring. A method of preparing enantiomerically-enriched samples of another phenyl/seven-member fused ring system, the benzothiazepines, is described by Higashikawa (JP 59144777) , where racemic benzothiazepine derivatives are optically resolved on a chromatographic column containing chiral crown ethers as a stationary phase. Although optical resolution is achieved, the Higashikawa method is limited to producing only small quantities of the enantiomerically-enriched benzothiazepine derivatives. Giordano (CA 2068231) reports the cyclization of (2S, 3S) -aminophenylthiopropionates in the presence of a phosphonic acid to produce (2S, 3S) -benzothiazepin-4-ones . However, that preparation is constrained by the need to use enantiomerically-enriched starting materials rather than racemic starting materials. In addition, the Giordano method controls the stereochemistry of the seven-member ring of the benzothiazepin-4-one only at the 2- and 3 -positions. The 4- and 5-positions of the seven-member ring of the benzothiazepin-4-one are not asymmetric centers, and the stereochemistry at these sites therefore cannot be controlled by the Giordano method. A method by which enantiomerically-enriched 1,5- benzothiazepin-3-hydroxy-4 (5H) -one compounds have been produced is through the asymmetric reduction of 1,5- benzothiazepin-3,4 (2H, 5H) -dione compounds, reported by Yamada, et al . (J“. Org. Chem. 1996, 61 (24), 8586-8590). The product is obtained by treating the racemic 1,5- benzothiazepin-3,4 (2H, 5H) -dione with the reaction product of an optically active alpha-amino acid and a reducing agent, for example sodium borohydride. Although a product with high optical purity was achieved, the method is limited by the use of a relatively expensive chemical reduction step.

The microbial reduction of racemic 1, 5-benzothiazepin- 3 , 4 (2H, 5H) -dione compounds to produce enantiomerically- enriched 1, 5-benzothiazepin-3-hydroxy-4 (5H) -one compounds is reported by Patel et al . , U.S. Patent 5,559,017. This method is limited by the inherent problems of maintaining a viable and pure bacterial culture of the appropriate species and variety. In addition, that method is limited in scale, producing only microgram quantities of the desired product. Until now, there have been no reported processes for preparing enantiomerically-enriched THBDO compounds or enantiomerically-enriched THBO compounds. Furthermore, there have been no reported processes for controlling the stereochemistry at the 4- and 5-positions of the seven- member rings of THBDO compounds or THBO compounds

FDA Grants Breakthrough Designation to Shire’s Rare GI Therapies

Tue, 06/14/2016

Shire announced that the U.S. Food and Drug Administration (FDA) has granted Breakthrough Therapy Designation for two investigational products for rare diseases: SHP621 (budesonide oral suspension, or BOS) for eosinophilic esophagitis (EoE), and SHP625 (maralixibat) for progressive familial intrahepatic cholestasis type 2 (PFIC2).

“Receiving Breakthrough Therapy Designation on two pipeline products this past week reflects the potential of our strong and innovative pipeline of more than 60 programs,” said Flemming Ornskov, M.D., MPH, and CEO, Shire. “Shire is committed to bringing innovation to the rare and specialty areas we focus on. We persevere to see compounds through the many stages of development through their challenges and successes, and always keep patients with unmet needs top of mind.”

EoE is a serious, chronic and rare disease that stems from an elevated number of eosinophils, a type of white blood cell, that infiltrate the walls of the esophagus. EoE is characterized by an inflammation of the esophagus that may lead to difficulty swallowing (dysphagia). The diagnosed prevalence of EoE ranges from approximately 15-55 cases per 100,000 persons, with high-end estimates reported by studies in Western regions.

PFIC refers to a group of autosomal-recessive liver disorders of childhood that disrupt bile formation and present with cholestasis. The symptoms of PFIC include severe itching of the skin (pruritus), and jaundice. PFIC is estimated to affect 1 in 50,000 to 1 in 100,000 births. PFIC2 is the most common type of PFIC, accounting for around half of cases.

According to the FDA, Breakthrough Therapy Designation is granted to a therapy that is intended to treat a serious or life-threatening disease or condition and preliminary clinical evidence indicates that the drug may demonstrate substantial improvement on one or more clinically significant endpoints over current standard of care. Under the designation, the FDA provides intensive guidance, organizational commitment involving senior managers, and eligibility for rolling and priority review of the application; this process helps ensure patients have access to therapies as soon as possible, pending approval. Breakthrough Therapy Designation does not guarantee that FDA will ultimately approve BOS for EoE or maralixibat for PFIC2, and the timing of any such approval is uncertain.

“On behalf of patients in the United States with EoE and PFIC2, we are so pleased that the FDA has granted Breakthrough Therapy Designation to BOS and maralixibat,” said Philip J. Vickers, Ph.D., Head of R&D, Shire. “We look forward to working with the agency to continue their development and, pending FDA approval, deliver these therapeutic options to the patients who need them most.”

It is well established that agents which inhibit the transport of bile acids across the tissue of the ileum can also cause a decrease in the levels of cholesterol in blood serum. Stedronski, in “Interaction of bile acids and cholesterol with nonsystemic agents having hypocholesterolemic properties,” Biochimica et Biophysica Acta, 1210 (1994) 255-287 discusses biochemistry, physiology, and known active agents surrounding bile acids and cholesterol. Bile acids are actively transported across the tissue of the ileum by an apical sodium co-dependent bile acid transporter (ASBT), alternatively known as an ileal bile acid transporter (IBAT).
A class of ASBT-inhibiting compounds that was recently discovered to be useful for influencing the level of blood serum cholesterol comprises tetrahydrobenzothiepine oxides (THBO compounds, PCT Patent Application No. WO 96/08484). Further THBO compounds useful as ASBT inhibitors are described in PCT Patent Application No. WO 97/33882.
Additional THBO compounds useful as ASBT inhibitors are described in U.S. Patent No. 5,994,391. Still further THBO compounds useful as ASBT inhibitors are described in PCT Patent Application No. WO 99/64409. Included in the THBO class are tetrahydrobenzo-thiepine-l -oxides and tetrahydrobenzothiepine- 1,1 -dioxides. THBO compounds possess chemical structures in which a phenyl ring is fused to a seven-member ring.

Published methods for the preparation of THBO compounds include the synthesis through an aromatic sulfone aldehyde intermediate. For example l-(2,2-dibutyl-3-oxopropylsulfonyl)-2-((4-methoxyphenyl)methyl)benzene (29) was cyclized with potassium t-butoxide to form tetrahydrobenzothiepine- 1,1 -dioxide (svn-24) as shown in Eq. 1.

Compound 29 was prepared by reacting 2-chloro-5-nitrobenzoic acid chloride with anisole in the presence of aluminum trichloride to produce a chlorobenzophenone compound; the chlorobenzophenone compound was reduced in the presence of trifluoromethanesulfonic acid and triethylsilane to produce a chlorodiphenylmethane compound; the
chlorodiphenylmethane compound was treated with lithium sulfide and 2,2-dibutyl-3-(methanesulfonato)propanal to produce l-(2,2-dibutyl-3-oxopropylthio)-2-((4-methoxyphenyl)methyl)-4-dimethylaminobenzene (40); and 40 was oxidized with m-chloroperbenzoic acid to produce 29. The first step of that method of preparing compound 29 requires the use of a corrosive and reactive carboxylic acid chloride that was prepared by the reaction of the corresponding carboxylic acid with phosphorus pentachloride.
Phosphorus pentachloride readily hydrolyzes to produce volatile and hazardous hydrogen chloride. The reaction of 2,2-dibutyl-3-(methanesulfonato)propanal with the lithium sulfide and the chlorodiphenylmethane compound required the intermediacy of a cyclic tin compound to make the of 2,2-dibutyl-3-(methanesulfonato)propanal. The tin compound is expensive and creates a toxic waste stream.
In WO 97/33882 compound syn-24 was dealkylated using boron tribromide to produce the phenol compound 28. Boron tribromide is a corrosive and hazardous material that generates hydrogen bromide gas and requires special handling. Upon hydrolysis, boron tribromide also produces borate salts that are costly and time-consuming to separate and dispose of.

An alternative method of preparing THBO compounds was described in WO
97/33882, wherein a 1,3-propanediol was reacted with thionyl chloride to form a cyclic sulfite compound. The cyclic sulfite compound was oxidized to produce a cyclic sulfate compound. The cyclic sulfate was condensed with a 2-methylthiophenol that had been deprotonated with sodium hydride. The product of the condensation was a (2-methylphenyl) (3′-hydroxypropyl)thioether compound. The thioether compound was oxidized to form an thioether aldehyde compound. The thioether aldehyde compound was further oxidized to form an aldehyde sulfone compound which in turn was cyclized in the presence of potassium t-butoxide to form a 4-hydroxytetrahydrobenzothiepine 1,1 -dioxide compound. This cyclic sulfate route to THBO compounds requires an expensive catalyst. Additionally it requires the use of SOCI2, which in turn requires special equipment to handle.
PCT Patent Application No. WO 97/33882 describes a method by which the phenol compound 28 was reacted at its phenol hydroxyl group to attach a variety of functional groups to the molecule, such as a quaternary ammonium group. For example, (4R,5R)-28 was reacted with l,4-bis(chloromethyl)benzene (?,??’-dichloro-p-xylene) to produce the chloromethyl benzyl- ether (4R,5R)-27. Compound (4R,5R)-27 was treated with diazabicyclo[2.2.2]octane (DABCO) to produce (4R,5R)-l-((4-(4-(3,3-dibutyl-7-(dimemylamino)-2,3,4,5-tetrahydro-4-hydroxy-l , 1 -dioxido-1 -benzothiepin-5-yl)phenoxy)methyl)phenyl)methyl-4-aza-l-azomabicyclo[2.2.2]octane chloride (41). This method suffers from low yields because of a propensity for two molecules of compound (4R,5R)-28 to react with one molecule of l,4-bis(chloromethyl)benzene to form a bis(benzothiepine) adduct. Once the bis-adduct forms, the reactive chloromethyl group of compound (4R,5R)-27 is not available to react with an amine to form the quaternary ammonium product.

A method of preparing enantiomerically enriched tetrahydrobenzothiepine oxides is described in PCT Patent Application No. WO 99/32478. In that method, an aryl-3- hydroxypropylsulfide compound was oxidized with an asymmetric oxidizing agent, for example (lR (->(8,9-dichloro-10-camphorsulfonyl)oxaziridine, to yield a chiral aryl-3-hydroxypropylsulfoxide. Reaction of the aryl-3-hydroxypropylsulfoxide with an oxidizing agent such as sulfur trioxide pyridine complex yielded an aryl-3-propanalsulfoxide. The aryl- 3-propanalsulfoxide was cyclized with a base such as potassium t-butoxide to
enantioselectively produce a tetrahydrobenzothiepine- 1 -oxide. The tetrahydrobenzothiepine- 1 -oxide was further oxidized to produce a tetrahydrobenzothiepine- 1 , 1 -dioxide. Although this method could produce tetrahydrobenzothiepine- 1,1 -dioxide compounds of high enantiomeric purity, it requires the use of an expensive asymmetric oxidizing agent.
Some 5-amidobenzothiepine compounds and methods to make them are described in

PCT Patent Application Number WO 92/18462.
In Svnlett. 9, 943-944(1995) 2-bromophenyl 3-benzoyloxy-l-buten-4-yl sulfone was treated with tributyl tin hydride and AIBN to produce 3-benzoyloxytetrahydrobenzothiepine-1,1 -dioxide.
In addition to forming the desired ASBT inhibitors, it is also desirable to form such

ASBT inhibitors of higher purity and having lower levels of residual solvent impurities. This is especially so with respect to ASBT inhibitors having a positively charged substituent, for example, the compounds designated as 41 (supra) and 60 (infra).
It is further desirable to provide methods for making such high purity ASBT inhibitors.

( 4R, 5R) -26
A 1000 mL 4 neck jacketed Ace reactor flask was fitted with a mechanical stirrer, a nitrogen inlet, an addition funnel or condenser or distilling head with receiver, a
thermocouple, four internal baffles and a 28 mm Teflon turbine agitator. The flask was purged with nitrogen gas and charged with 25.0 grams of (4R,5R)-28 and 125 mL of N,N-dimethylacetamide (DMAC). To this was added 4.2 grams of 50% sodium hydroxide. The mixture was heated to 50°C and stiπed for 15 minutes. To the flask was added 8.3 grams of 55 dissolved in 10 mL of DMAC, all at once. The temperature was held at 50°C for 24 hrs. To the flask was added 250 mL of toluene followed by 125 mL of dilution water. The mixture was stiπed for 15 minutes and the layers were then allowed to separate at 50°C. The flask was then charged with 125 mL of saturated sodium chloride solution and stiπed 15 minutes. Layers separated cleanly in 30 seconds at 50°C. Approximately half of the solvent was distilled off under vacuum at 50°C. The residual reaction mixture contained (4R,5R)-26.

Step 2. Preparation of (4R.5RV27.

( 4R, 5R) -27
Toluene was charged back to the reaction mixture of Step 1 and the mixture was cooled to 35°C. To the mixture was then added 7.0 grams of thionyl chloride over 5 minutes. The reaction was exothermic and reached 39°C. The reaction turned cloudy on first addition of thionyl chloride, partially cleared then finally remained cloudy. The mixture was stirred for 0.5 hr and was then washed with 0.25N NaOH. The mixture appeared to form a small amount of solids that diminished on stirring, and the layers cleanly separated. The solvent was distilled to a minimum stir volume under vacuum at 50°C. The residual reaction mixture contained (4R,5R)-27.

Step 3. Preparation of 41.
To the reaction mixture of Step 2 was charged with 350 mL of methyl ethyl ketone (MEK) followed by 10.5 mL water and 6.4 grams of diazabicyclo[2.2.2]octane (DABCO) dissolved in 10 mL of MEK. The mixture was heated to reflux, and HPLC showed <0.5% of (4R,5R)-27. The reaction remained homogenous initially then crystallized at the completion of the reaction. An additional 5.3 mL of water was charged to the flask to redissolve product. Approximately 160 mL of solvent was then distilled off at atmospheric pressure. The mixture started to form crystals after 70 mL of solvent was distilled. Water separated out of distillate indicating a ternary azeotrope between toluene, water and methyl ethyl ketone (MEK). The mixture was then cooled to 25°C. The solids were filtered and washed with 150 mL MEK, and let dry under vacuum at 60°C. Isolated 29.8.0 g of off-white crystalline 4 Example 11a.
Alternate Preparation of (4R,5R)-l-((4-(4-(3,3-dibutyl-7-(dimemylamino)-2,3,4,5-tetrahydro- 4-hydroxy- 1 , 1 -dioxido- 1 -benzithiepin-5-yl)phenoxy)methyl)phenyl)methyl-4-aza- 1 – azoniabicyclo[2.2.2]octane chloride, Form II of 41

A 1000 mL 4 neck jacketed Ace reactor flask is fitted with a mechanical stiπer, a nitrogen inlet, an addition funnel or condenser or distilling head with receiver, a
thermocouple, four internal baffles and a 28 mm Teflon turbine agitator. The flask is purged with nitrogen gas and charged with 25.0 grams of (4R,5R)-28 and 100 mL of N,N-dimethylacetamide (DMAC). The mixture is heated to 50°C and to it is added 4.02 grams of 50% sodium hydroxide. The mixture is stiπed for 30 minutes. To the flask is added 8.7 grams of 55 dissolved in 12.5 mL of DMAC, all at once. The charge vessel is washed with 12.5 mL DMAC and the wash is added to the reactor. The reactor is stiπed for 3 hours. To the reactor is added 0.19 mL of 49.4% aq. NaOH and the mixture is stirred for 2 hours. To the mixture is added 0.9 g DABCO dissolved in 12.5 mL DMAC. The mixture is stiπed 30 to 60 minutes at 50°C. To the flask is added 225 mL of toluene followed by 125 mL of dilution water. The mixture is stiπed for 15 minutes and the layers are then allowed to separate at 50°C. The bottom aqueous layer is removed but any rag layer is retained. The flask is then charged with 175 mL of 5% hydrochloric acid solution and stiπed 15 minutes. Layers are separated at 50°C to remove the bottom aqueous layer, discarding any rag layer with the aqueous layer. Approximately half of the solvent is distilled off under vacuum at a maximum pot temperature of 80°C. The residual reaction mixture contains (4R,5R)-26.

Step 2. Preparation of (4R.5RV27.

Toluene (225 mL) is charged back to the reaction mixture of Step 1 and the mixture is cooled to 30°C. To the mixture is then added 6.7 grams of thionyl chloride over 30 to 45 minutes. The temperature is maintained below 35°C. The reaction turns cloudy on first addition of thionyl chloride, then at about 30 minutes the layers go back together and form a clear mixture. The mixture is stiπed for 0.5 hr and is then charged with 156.6 mL of 4% NaOH wash over a 30 minute period. The addition of the wash is stopped when the pH of the mixture reaches’ 8.0 to 10.0. The bottom aqueous layer is removed at 30°C and any rag layer is retained with the organic layer. To the mixture is charged 175 mL of saturated NaCl wash with agitation. The layers are separated at 30°C and the bottom aqueous layer is removed, discarding any rag layer with the aqueous layer. The solvent is distilled to a minimum stir volume under vacuum at 80°C. The residual reaction mixture contains (4R,5R)-27.

Step 3. Preparation of 41.
To the reaction mixture of Step 2 is charged 325 mL of methyl ethyl ketone (MEK) and 13 mL water. Next, the reactor is charged 6.2 grams of diazabicyclo[2.2.2]octane (DABCO) dissolved in 25 mL of MEK. The mixture is heated to reflux and held for 30 minutes. Approximately 10% of solvent volume is then distilled off. The mixture starts to form crystals during distillation. The mixture is then cooled to 20°C for 1 hour. The off-white crystalline 41 (Form U) is filtered and washed with 50 mL MEK, and let dry under vacuum at 100°C.

A 1000 mL 4 neck jacketed Ace reactor flask is fitted with a mechanical stiπer, a nitrogen inlet, an addition funnel or condenser or distilling head with receiver, a
thermocouple, four internal baffles and a Teflon turbine agitator. The flask is purged with nitrogen gas and charged with 25.0 grams of (4R,5R)-28 and 125 mL of N,N-dimethylacetamide (DMAC). The mixture is heated to 50°C and to it is added 7.11 grams of 30% sodium hydroxide over a period of 15 to 30 minutes with agitation. The mixture is stiπed for 30 minutes. To the flask is added 9.5 grams of solid 55. The reactor is stiπed for 3 hours. To the mixture is added 1.2 g of solid DABCO. The mixture is stiπed 30 to 60 minutes at 50°C. To the flask is added 225 mL of toluene followed by 125 mL of water. The mixture is stirred for 15 minutes and the layers are then allowed to separate at 50°C. The bottom aqueous layer is removed but any rag layer is retained with the organic layer. The flask is then charged with 175 mL of 5% hydrochloric acid solution and stirred 15 minutes. Layers are separated at 50°C to remove the bottom aqueous layer, discarding any rag layer with the aqueous layer. The flask is then charged with 225 mL of water and stirred 15 minutes. The layers are allowed to separate at 50°C. The bottom aqueous layer is removed, discarding any rag layer with the aqueous layer. Approximately half of the solvent is distilled off under vacuum at a maximum pot temperature of 80°C. The residual reaction mixture contains (4R,5R)-26.

Step 2. Preparation of (4R.5RV27.

Toluene (112.5 mL) is charged back to the reaction mixture of Step 1 and the mixture is cooled to 25°C. To the mixture is then added 7.3 grams of thionyl chloride over 15 to 45 minutes. The temperature of the mixture is maintained above 20°C and below 40°C. The reaction turns cloudy on first addition of thionyl chloride, then at about 30 minutes the layers go back together and form a clear mixture. The mixture is then charged with 179.5 mL of 4% NaOH wash over a 30 minute period. The mixture is maintained above 20°C and below 40°C during this time. The addition of the wash is stopped when the pH of the mixture reaches 8.0 to 10.0. The mixture is then allowed to separate at 40°C for at least one hour.

The bottom aqueous layer is removed and any rag layer is retained with the organic layer. To the mixture is charged 200 mL of dilution water. The mixture is stiπed for 15 minutes and then allowed to separate at 40°C for at least one hour. The bottom aqueous layer is removed, discarding any rag layer with the aqueous layer. The solvent is distilled to a minimum stir volume under vacuum at 80°C. The residual reaction mixture contains (4R,5R)-2 .

Step 3. Preparation of 41.
To the reaction mixture of Step 2 is charged 350 mL of methyl ethyl ketone (MEK) and 7 mL water. The mixture is stiπed for 15 minutes and the temperature of the mixture is adjusted to 25°C. Next, the reactor is charged with 6.7 grams of solid
diazabicyclo[2.2.2]octane (DABCO). The mixture is maintained at 25°C for three to four hours. It is then heated to 65°C and maintained at that temperature for 30 minutes. The mixture is then cooled to 25°C for 1 hour. The off-white crystalline 41 (Form II) is filtered and washed with 50 mL MEK, and let dry under vacuum at 100°C.

(4R,5R)-27 (2.82 kg dry basis, 4.7 mol) was dissolved in MTBE (9.4 L). The solution of (4R,5R)-22 was passed through a 0.2 mm filter cartridge into the feeding vessel. The flask and was rinsed with MTBE (2 x 2.5 L). The obtained solution as passed through the cartridge filter and added to the solution of (4R,5R)-2 in the feeding vessel. DABCO
(diazabicyclo[2.2.2]octane, 0.784 kg, 7.0 mol) was dissolved in MeOH (14.2 L). The DABCO solution was passed through the filter cartridge into the 100 L nitrogen-flushed reactor. The Pyrex bottle and the cartridge filter were rinsed with MeOH (7.5 L) and the solution was added to the reactor. The (4R,5R)-22 solution was added from the feeding vessel into the reactor at 37°C over a period of 10 min, while stirring. Methanol (6.5 L) was added to the Pyrex bottle and via the cartridge filter added to the feeding vessel to rinse the remaining (4R,5R)-2 into the reactor. The reaction mixture was brought to 50-60°C over 10-20 min and stiπed at that temperature for about 1 h. The mixture was cooled to 20-25°C over a period of 1 h. To the reaction mixture, methyl t-butyl ether (MTBE) (42 L) was added over a period of 1 h and stiπed for a minimum of 1 h at 20 – 25°C. The suspension was filtered through a Buchner funnel. The reactor and the filter cake were washed with MTBE (2 x 14 L). The solids were dried on a rotary evaporator in a 20 L flask at 400 – 12 mbar, 40°C, for 22 h. A white crystalline solid was obtained. The yield of 4 . (Form I) was 3.08 kg (2.97 kg dry, 93.8 %) and the purity 99.7 area % (HPLC; Kromasil C 4, 250 x 4.6 mm column; 0.05% TFA in H2O/0.05% TFA in ACN gradient, UV detection at 215 nm).

Example 12a.
Conversion of Form I of Compound 41 into Form II of Compound 41.

To 10.0 grams of Form I of 4 . in a 400 mL jacketed reactor is added 140 mL of MEK. The reactor is stirred (358 φm) for 10 minutes at 23 °C for 10 minutes and the stirring rate is then changed to 178 φm. The suspension is heated to reflux over 1 hour using a programmed temperature ramp (0.95°C/minute) using batch temperature control (cascade mode). The delta Tmaχ is set to 5°C. The mixture is held at reflux for 1 hour. The mixture is cooled to

25°C. After 3 hours at 25°C, a sample of the mixture is collected by filtration. Filtration is rapid (seconds) and the filtrate is clear and colorless. The white solid is dried in a vacuum oven (80°C, 25 in. Hg) to give a white solid. The remainder of the suspension is stirred at 25°C for 18 hours. The mixture is filtered and the cake starts to shrink as the mother liquor reaches the top of the cake. The filtration is stopped and the reactor is rinsed with 14 mL of MEK. The reactor stirrer speed is increased from 100 to 300 φm to rinse the reactor. The rinse is added to the filter and the solid is dried with a rapid air flow for 5 minutes. The solid is dried in a vacuum oven at 25 in. Hg for 84 hours to give Form II of 4

Abstract

In the preceding paper several compounds were reported as potent apical sodium-codependent bile acid transporter (ASBT) inhibitors. Since the primary site for active bile acid reabsorption is via ASBT, which is localized on the luminal surface of the distal ileum, we reasoned that a nonsystemic inhibitor would be desirable to minimize or eliminate potential systemic side effects of an absorbed drug. To ensure bioequivalency and product stability, it was also essential that we identify a nonhygroscopic inhibitor in its most stable crystalline form. A series of benzothiepines were prepared to refine the structure−activity relationship of the substituted phenyl ring at the 5-position of benzothiepine ring and to identify potent, crystalline, nonhygroscopic, and efficacious ASBT inhibitors with low systemic exposure.

a All compounds were prepared using method B in Scheme 3.b Taurocholate is transported across the baby hamster kidney cell membrane.c % weight gain in a 25 °C, 57% humidity chamber for 2 weeks.d % weight gain in a 40 °C, 80% humidity chamber for 2 weeks.e Crystallinity as determined by X-ray powder diffraction analysis.f (N+)DB is a DABCO terminal group with the quaternary ammonium attached to the linke

Step 3a. Preparation of 2 , 2-dibutyl-l, 3-propanediol . To a stirred solution of di-butyl-diethylmalonate (Aldrich) (150g, 0.55 mol in dry THF (700ml) in an acetone/dry ice bath was added LAH (1 M THF) 662 ml (1.2 eq. , 0.66 mol) dropwise maintaining the temperature between -20 to 0°C. The reaction was stirred at RT overnight. The reaction was cooled to -20°C and 40 ml of water, and 80 mL of 10% NaOH and 80 ml of water were added dropwise. The resulting suspension was filtered. The filtrate was dried over sodium sulphate and concentrated in vacuo to give diol 598.4 g (yield 95%) as an oil. MS spectra and proton and carbon NMR spectra were consistent with the product.

Step 3b. Preparation of dibutyl cyclic sulfite

A solution of 2 , 2-dibutyl-l, 3-propanediol (103 g, 0.548 0 mol, obtained from Step 3a) and triethylamine (221 g, 2.19 mol) in anhydrous methylene chloride (500 ml) was stirred at 0°C under nitrogen. To the mixture, thionyl chloride (97.8* g, 0.‘82 mol) was added dropwise and within 5 min the solution turned yellow and then black when the addition was 5 completed within half an hour. The reaction mixture was stirred for 3 hrs. at 0°C. GC showed that there was no starting material left. The mixture was washed with ice water twice then with brine twice . The organic phase was dried over magnesium sulfate and concentrated under vacuum 0 to give 128 g (100%) of the dibutyl cyclic sulfite as a black oil. Mass spectrum (MS) was consistent with the product .

To a solution of the dibutyl cyclic sulfite (127.5 g , 0.54 mol, obtained from Step 3b) in 600 ml acetonitrile and 500 ml of water cooled in an ice bath under nitrogen was added ruthenium (III) chloride (1 g) and sodium periodate 0 (233 g, 1.08 mol) . The reaction was stirred overnight and the color of the solution turned black. GC showed that there was no starting material left. The mixture was extracted with 300 ml of ether and the ether extract was washed three times with brine. The organic phase was dried over magnesium sulfate and passed through celite. The filtrate was 5 concentrated under vacuum and to give 133 g (97.8%) of the dibutyl cyclic sulfate as an oil. Proton and carbon NMR and MS were consistent with the product.

15 dibutyl cyclic sulfate (obtained from Step 3c) was added at 0°C and stirred for 10 minutes. The mixture was allowed to warm up to room temperature and stirred overnight. The solvent was evaporated and 200 mL of water was added. The solution was washed with 200 mL of diethyl ether and added

2025 mL of concentrated sulfuric acid to make a 2.0 M solution that was refluxed overnight. The solution was extracted with ethyl acetate and the organic solution was dried over MgS04 and concentrated in vacuo. The crude aryl-3 – hydroxypropylsulfide was purified by silica gel

To a stirred solution of 20.00 g (47.78 mmol) of aryl- 53 -hydroxypropylsulfide (obtained from Step 4) in 1 L of methylene chloride was added 31.50 g of 96% (12?) – ( -) – (8 , 8- dichloro-10-camphor-sulfonyl) oxaziridine (100.34 mmol, Aldrich) at 2°C. After all the oxaziridine dissolved the mixture was placed into a -30 °C freezer for 72 hours. The

10 solvent was evaporated and the crude solid was washed with 1 L of hexane. The white solid was filtered off and the hexane solution was concentrated in vacuo. The crude oil was purified on a silica gel column (Waters Prep 500) using 15% ethyl acetate/hexane to afford 19.00 g (95%) of the

207.00 (d, J = 8.1 Hz, 2H) , 7.18-7.23 (m, IH) , 7.99-8.04 (m, IH) . Enantiomeric excess was determined by chiral HPLC on a (2?,2?) -Whelk-0 column using 5% ethanol/hexane as the eluent. It showed to be 78% e.e. with the first eluting peak as the major product.

To a stirred solution of 13.27 g of triethylamine (131.16 mmol, Aldrich) in 200 mL dimethyl sulfoxide were

30 added 19.00 g (43.72 mmol) of enantiomerically-enriched aryl-3 -hydroxypropylsulfoxide (obtained from Step 5) and 20.96 g of sulfur trioxide-pyridine (131.16 mmol, Aldrich) at room temperature. After the mixture was stirred at room temperature for 48 hours, 500 mL of water was added to the mixture and stirred vigorously. The mixture was then 5 extracted with 500 mL of ethyl acetate twice. The ethyl acetate layer was separated, dried over MgS04, and concentrated in vacuo. The crude oil was filtered through 500 mL of silica gel using 15% ethyl acetate/hexane to give 17.30 g (91%) of the enantiomerically-enriched aryl-3-

20 To a stirred solution of 17.30 g (39.99 mmol) of enantiomerically-enriched aryl-3 -propanalsulfoxide (obtained from Step 6) in 300 mL of dry THF at -15°C was added 48 mL of 1.0 M potassium t-butoxide in THF (1.2 equivalents) under nitrogen. The solution was stirred at -15°C for 4 hours.

25 The solution was then quenched with 100 mL of water and neutralized with 4 mL of concentrated HCl solution at 0°C. The THF layer was separated, dried over MgS04, and concentrated in vacuo. The enantiomerically-enriched tetrahydrobenzothiepine-1-oxide (4R,5R) was purified by

15 Sigma) at 0 °C. After stirring at 0 °C for 2 hours, the mixture was allowed to warm up to room temperature and stirred for 4 hours. 50 mL of saturated Na2S03 was added into the mixture and stirred for 30 minutes. The solution was then neutralized with 50 mL of saturated NaHC03 solution.

20 IH) . The product was determined to have 78% e.e. by chiral HPLC on a Chiralpak AD column using 5% ethanol/hexane as the eluent. Recrystallization of this solid from ethyl acetate/hexane gave 1.70 g of the racemic product. The remaining solution was concentrated and recrystallized to

25 give 9.8 g of colorless solid. Enantiomeric excess of this solid was determined by chiral HPLC on a Chiralpak AD column using 5% ethanol/hexane as the eluent. It showed to have 96% e.e with the first eluting peak as the major product.

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DR ANTHONY MELVIN CRASTO, Born in Mumbai in 1964 and graduated from Mumbai University, Completed his Ph.D from ICT, 1991,Matunga, Mumbai, India, in Organic Chemistry, The thesis topic was Synthesis of Novel Pyrethroid Analogues, Currently he is working with GLENMARK PHARMACEUTICALS LTD, Research Centre as Principal Scientist, Process Research (bulk actives) at Mahape, Navi Mumbai, India. Total Industry exp 29 plus yrs, Prior to joining Glenmark, he has worked with major multinationals like Hoechst Marion Roussel, now Sanofi, Searle India Ltd, now RPG lifesciences, etc. He has worked with notable scientists like Dr K Nagarajan, Dr Ralph Stapel, Prof S Seshadri etc, He did custom synthesis for major multinationals in his career like BASF, Novartis, Sanofi, etc., He has worked in Discovery, Natural products, Bulk drugs, Generics, Intermediates, Fine chemicals, Neutraceuticals, GMP, Scaleups, etc, he is now helping millions, has 9 million plus hits on Google on all Organic chemistry websites. His friends call him worlddrugtracker. His New Drug Approvals, Green Chemistry International, All about drugs, Eurekamoments, Organic spectroscopy international,
etc in organic chemistry are some most read blogs He has hands on experience in initiation and developing novel routes for drug molecules
and implementation them on commercial scale over a 29 year tenure till date Aug 2016, Around 30 plus products in his career. He has good knowledge of IPM, GMP, Regulatory aspects, he has several International patents published worldwide . He has good proficiency in Technology transfer, Spectroscopy, Stereochemistry, Synthesis, Polymorphism etc., He suffered a paralytic stroke/ Acute Transverse mylitis in Dec 2007 and is 90 %Paralysed, He is bound to a wheelchair, this seems to have injected feul in him to help chemists all around the world, he is more active than before and is pushing boundaries, He has 9 million plus hits on Google, 2.5 lakh plus connections on all networking sites, 25 Lakh plus views on dozen plus blogs, He makes himself available to all, contact him on +91 9323115463, email amcrasto@gmail.com, Twitter, @amcrasto , He lives and will die for his family, 90% paralysis cannot kill his soul., Notably he has 13 lakh plus views on New Drug Approvals Blog in 212 countries......https://newdrugapprovals.wordpress.com/ , He appreciates the help he gets from one and all, Friends, Family, Glenmark, Readers, Wellwishers, Doctors, Drug authorities, His Contacts, Physiotherapist, etc

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